Contact for electrical connector

ABSTRACT

An electrical connector that includes an insert having continuous openings between the forward and rearward ends, each of the openings receiving a contact which is retained between a rearwardly facing shoulder in each opening and integral resilient fingers on the insert, which incline forwardly and inwardly from the circumferential wall of the opening to engage the rear contact shoulder, which is undercut to stabilize the ends of the fingers and improve contact retention.

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[ CUNTACT iron ELECTRHCAL [56] lReterences Cited @WNEETUR uwmzo STATESPATENTS [75] Inventor: Kenneth Ml. Clnrllt, Beaumont, Calif. 3,336.56)8/t967 Nava 339/94 M 3,721,943 3 I973 C 339 94 M [73] Assignee: The llleutsch Company Electronic E E Dnvnsmn Bannmg Primary Examiner-Joseph H.McGlynn a l Attorney-Richard F. Carr et a]. [22] Filed: Apr. 41, 1973 21Appl. No.: M7303 [57] ABSTRACT An electrical connector that includes aninsert having I Relmed Apphcatmn Dam continuous openings between theforward and rear- DWISIO" of f 3l t f y 2 1 3 ward ends, each of theopenings receiving a contact 2 gg ;j s i which is retained between arearwardly facing shoulan der in each opening and integral resilientfingers on the insert, which incline forwardly and inwardly from 2% thecircumferential wall of the opening to engage the E LM 276 rear contactshoulder, which is undercut to stabilize the ends of the fingers andimprove contact retention.

4- Claims, 15 Drawing Figures PATENTEU 8 4 SHEET 1 BF E PMEWEWN @1914318,966

SHEET 0F CONTACT TUTTI ELETJTTTMZAL ETlJNNlE'CTUR REFERENCE TO RELATEDAPPLlCATlONS This is a division of my copending patent application Ser.No. 167,317, filed July 29, 1971, for Electrical Connector now US. Pat.No. 3,727,172, which is a continuation--in-part of application Ser. No.83,782, filed Oct. 26, 1970, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to electrical connectors.

2. The Prior Art Some electrical connectors provide for rear insertionand release of the electrical contacts, a desirable feature facilitatingthe assembly and servicing of the connector. In these connectors, eachcontact opening includes a rearwardly facing shoulder. There is, inaddition, a metal retaining clip that fits within the opening, having asplit outer sleeve portion received between shoulders defined by acircumferential recess in the wall of the opening, while spring fingersincline forwardly and inwardly from the sleeve portion of the retainerclip. The contact includes an annular enlargement that defines forwardlyand rearwardly facing shoulders. The contact is held in the insert ofthe con nector by positioning its forwardly facing shoulder adjacent therearwardly facing shoulder of the insert and the rearward shoulder ofthe contact against the ends of the spring fingers of the retainingclip. US. Pat. No. 3,158,424 provides an illustration of this contactretention system.

The necessity for utilizing a separate retainer clip for each contactadds considerably to the number of parts incorporated in the connector.This increases the expense of the connector as well as the requiredassembly time. The possibility is always present of an improperinstallation of a retainer clip (such as positioning it backwards),which will prevent it from correctly retaining the contact. The retainerclips also are fragile and very difficult to handle, particularly whenused for connectors of small sizes.

In the past, it was proposed to use integral fingers on the dielectricinsert to engage the rearward shoulder of the contact, instead ofproviding a separate metal retaining clip. This design had an insertthat was in two sections bonded together. The connection of the insertsections was made around the periphery of the insert assembly, whileinteriorly the rearward radial face of the forward insert element wasspaced from the for ward face of the rearward insert element. This leftan open cavity extending the entire interior transverse di' mension ofthe insert unit. Thus, there was a connection between the adjacentcontact openings, and the openings were not continuous from front torear, but interrupted by the cavity. The integral retention fingersprojected forwardly from the forward face of the rearward insert elementinto the interior cavity, stopping short of the rearward face of theforward insert section. This provided the means for holding the contactsin place, with the fingers engaging the rearward contact shoulders, andthe rearward face of the forward insert engaging the forward contactshoulders.

This design had certain disadvantages and was not successfulcommercially. The open cavity within the insert meant that the dangerexisted that a contact could become misaligned and cocked so that itengaged the adjacent contact to result in a short circuit. Also, a probeor other tool inserted into the connector could move from one contactopening to the adjacent one through the open cavity space, raisingfurther risk of bending or damaging the contacts or misaligning them sothat they would not mate properly or could result in a short circuit.Any moisture that found its way into the insert could travel to all ofthe contact openings rather than being confined to only one as where thecontact openings are separated. Furthermore, the inserts of theseconnectors were made of nylon, which absorbed moisture and lost itsstrength when exposed to water, and could not withstand elevatedtemperatures.

Particularly in the design ofa relatively small connector with integralplastic fingers, a severe problem arises in making the plastic fingersadequately strong to resist the rearward forces imposed on. the contactwithout buckling and breaking. The retention fingers are loaded ascolumns, and, because their outer ends are free for engagement with thecontact shoulder, they ordinarily lack stability. This, in turn, reducesthe loading that they can withstand before buckling. Also retentionfingers of conventional configuration are loaded eccentrically to theirneutral column centers, increasing the tendency to buckle under load.The relatively thin fingers additionally are subject to possible failurein shear or may break from an inability to flex properly.

SUMMARY OF THE INVENTlON The present invention provides an improvedelectrical connector which overcomes the difficulties outlined above.Within the insert of the plug and of the receptacle, which is made of amoistureand temperatureresistant plastic, are integral resilient fingersin each of the contact openings. The forward ends of the fingers aremade thicker than the bases of the fingers, and provided with radialedges to engage the contact shoulders. The finger ends also includeinner surfaces that are cylindrical segments to complementarily engagethe barrels of the contacts. This stabilizes the ends of the fingers toincrease their column strength. The larger cross-sectional area at thefinger ends provides greater strength and load-carrying capacity both inbending and in shear. The thinner base portions of the fingers haverequisite flexibility to allow contact insertion and removal withoutsuffering damage.

The metal contact retained by the integral plastic fingers generallyresembles those of conventional type. However, its rearward shoulder isnot radial but, instead, is undercut. This gives it a frustoconicalconfiguration as it tapers toward the forward end of the contact.

This combination provides substantially improved strength for theintegral plastic retaining fingers so that they may be usedsatisfactorily even in small-sized eonnectors, and a separate metal clipis not required. The undercut shoulder has the effect of stabilizing thefree end of the finger so that the fingers column strength is enhancedsignificantly. lncreasedl stability also is realized from thecomplementary engagement of the cylindrical segmental surface of thefinger with the periphery of the contact. The undercut shoulder helpskeep the cylindrical segmental surface properly engaged with the contactsurface to increase the stability of the finger. The stabilizing effectis improved by the fact that the plastic of the finger is softer thanthe metal of ward portions of the inner circumferential wall 2i of theplug shell.

The pin contacts T3 are received in spaced parallel openings 3% formedin the insert assembly l2. The openings Eli are continuous from thefront to the rear of the insert assembly 12, and are separated from eachother so that there is no communiction from one opening 3% to the other.The connector is designed so that a large number of the pin contacts l3may be retained in close adjacency, but, for clarity of illustration,only a relatively few such contacts are shown in the drawing.

Each opening 38 includes a relatively wide-diameter portion 39 at therearward end of the plastic disk which, through a frustoconical portionill, tapers forwardly to a portion ll of smaller diameter. A pluralityof fingers l2 extends radially inwardly and axially forwardly from theportion ll of the opening 3t; into the continuation d3 of the opening 3%in the member 15.. This positions the fingers l2 inwardly and radiallyopposite the circumferential wall of the portion d3 of the opening Thefingers 452 are shorter than the section 413 of the opening, so thattheir forward ends are inwardly ofthe forward radial face 44 of themember l5. There are four of the fingers 42 in the example shown, asillustrated in H6. 8. The fingers 4l2 are rounded transversely so thatcollectively they define a generally frustoconical shape with narrowspaces between adjacent fingers. While the plastic member llil isrelatively hard and rigid, the fingers 4i?! are thin and, therefore,resilient. A radial shoulder is formed by the rearward face d5 of themember lll where the diameter of the opening decreases at portion as. inthe gasket member 16, the opening has a relatively wide-diameter portion$7 at the rearward end and a smaller-diameter portion 48 at the forwardend.

An opening W in the rearward sealing member 35 communicates with each ofthe openings 38.

The pin contacts 113 may be of conventional construction, includinghollow, longitudinally elongated barrel portions 50 at their rearwardends, which receive the ends ofwires 511 from which the insulation hasbeen stripped. The contact barrels fill are crimped to the wires Sll toform a mechanical and electrical connection. The wires fill enter theopenings 33 through the openings W in the rearward member 35, beingengaged by annular sealing beads 52 formed on the circumference of theopening l9.

Forwardly of the barrel portion 5ft, each contact l3 includes a part 53%of enlarged diameter which defines forward and rearward shoulders 54 and55, respectively. Beyond the forward shoulder 54., the contact narrowsto a projecting pin portion 56 that is adapted to enter the socketcontact When installed in the opening 3%, the forward shoulder 54 of thecontact is adjacent the rearwardly facing shoulder defined by therearward face 45 of the insert Ml, which thereby prevents forwardmovement of the contact l3.

In this manner, the contact is positioned within the insert assembly andsecurely retained. With the use of the integral fingers 4-2, it isunnecessary to provide any auxiliary metal clip for retaining thecontact, as in conventional connector construction. This simplifies themanufacture of the connector and lowers its cost. The danger of animproperly installed retainer clip is obvi ated. With the fingers d2being entirely received in the section 43 of the opening 38, whichlocates them rearwardly of the forward face d4 of the disk llfi, thebonding together of the inserts l t and its will not adversely affectthe fingers. in other words, the fingers are remote from the bond lineso that any excess bonding material squeezed out at the joint will notinterfere with the movement of the fingers.

As best seen in the enlarged illustration of HG. lltl, the fingers 4 2are thicker in cross section at their forward ends than they are attheir points of attachment to the insert 15, being tapered gradually inthickness to the rear. Also, each finger has a substantially radialforward end surface 57 which connects at a right angle to an inner endsurface 58, which is a cylindrical segment generally complementary tothe barrel S ill of the contact 113. When the finger ill engages thecontact l3, the radial end surface 5'7 fits behind the rearward shoulder55 of the contact, while the inner end surface 58 of the finger restsupon the barrel 5t) adjacent the shoulder 55.

The rearward transverse shoulder 55 of the contact 13 does not fallwithin a radial plane. instead, it is inclined toward the forward end ofthe contactr Consequently, the shoulder 55 is undercut, being defined bya frustuin of a cone. Desirable results are achieved when the shoulder55 is inclined at around 12 relative to a radial plane. When the contacti3 is subjected to a force pushing it toward the rear, the undercutshoulder configuration and the inner finger surfaces 58 contributegreatly to the amount of force which can be ab sorbed before theretention fingers d2 will fail.

With the arrangement of this invention, the fingers l2, loaded ascolumns, receive the forces on them near the neutral centers of thecolumns, minimizing the tendency to buckle. The plastic of the fingersl2, being softer than the metal of the contact l3, becomes distortedwhere it engages the radially outer portion of the shoulder 55., asillustrated in particular in the enlarged view of FIG. l2. This has theeffect of embedding the shoulder in the outer ends of the plasticfingers l2, stabilizing the finger ends. This increases the columnstrength of the fingers lli because a column can with stand more loadingif its ends are stabilized.

An additional stabilizing effect is realized because of the arcuateinner surfaces 5% of the fingers d2 substantially complementarilyengaging the periphery of the barrel St) of the contact adjacent thebase of the shoulder @5. This helps to anchor the free ends of thefingers. The inclined configuration of the shoulder 55 results in aforce component on the fingers ll, helping to hold the surfaces 53tightly against the circumference of the barrel 5ft to enhance thecolumn stabilizing effect.

The greater wall thickness of the fingers at their outer ends adds totheir strength in shear and in bending. The bending strength resists thebuckling of the fingers under load.

Another advantage comes from the fact that the inner corner 59 of thefinger 12, between the end surface 57 and the inner surface 5%, becomesspaced rear wardly from the fillet so, which necessarily is formedbetween the shoulder 55 and the barrel 5ft when the contact lift ismachined. When there is a straight radial shoulder, the inner corners ofthe retention fingers will engage the fillet at the base of theshoulder. This deflects the fingers outwardly, thereby tending to camthe fingers out of engagement with the shoulder. The undercut shoulder55 permits the finger to clear the fillet so without requiring a recessin the finger and without sacrifice in the strength of the fingers.

The insert assembly 61 for the receptacle includes a plastic disk 62that is similar to the member 15. To it is bonded or otherwise suitablysecured a forward cover disk 63. The members 62 and 63 also may be madeof Astrel 360 plastic. Outwardly projecting lugs 64 on the disk 62correspond to the lugs 18 on the member 15. The lugs 6 1 secure theinsert assembly 61 to the receptacle shell 65 in the same way that thelugs 18 attach the insert assembly 12 in the plug shell 11. The insertassembly 61 is introduced into the receptacle shell 65 by passing thelugs 64- through axial grooves in the inner surface of the receptacleshell 65, whereupon subsequent rotation of the insert assembly 61 placesthe lugs 64 between opposed forward and rearward shoulders 66 and 67,respectively, in the receptacle shell. This holds the disk 62 and thecover element 63 within the receptacle.

The socket contacts 63 are retained in continuous separate openings 69in the insert assembly of the receptacle, positioned against axialrearward movement by integral fingers 70 that project forwardly andinwardly from the insert disk 62. A shoulder '71 on the insert member63, where the opening 69 reduces in width, is adjacent the forward endof the contact 69 and precludes forward movement of the contact. Thefingers 70 are engageable with the rearward edge of the annularenlargement 72 on the socket contact. A wire 73 extends inwardly throughan opening 74 in the rearward sealing member 75 of the receptacle 10 foreach of the socket contacts 68. The end portions ofthe wires 73 arestripped of insulation and connected by crimp ing to the rearward barrelends '76 of the socket contacts 68. When the forward ends 77 of thesocket contacts receive the projecting pin portions 56 of the pincontacts 13 upon the mating of the connector, cir cuits are completedbetween the wires 51 and 73.

A rounded annular bead 78 projects outwardly from the forward radialface 79 of the cover disk 63 of the receptacle insert around each of theopenings 69. The bead 78 is engaged by the flat forward face 80 of thegasket 16 on the plug 9 when the connector is in the assembled position.Consequently, the bead 78 displaces the resilient material of the gasket16 and an efficient moisutre seal is produced. This type of seal doesnot rely upon the entry of a projecting part of the resilient elastomerinta recess in the hard plastic of the mating part as in some prior-artdesigns. Unlike the previous designs, swelling of the gasket 16 fromattack of fluids will not appreciably interfere with the mating of theconnector so that the axial force required will not vary significantlyunder those conditions.

The mechanism for securing the plug and receptacle together in the matedposition includes a coupling ring 81 that circumscribes the plug shell11. The rearward end of the coupling ring includes a radially inwardlyextending flange 02 in back of a rearwardly facing shoulder 83 on theplug shell. A snap ring 84 fits in an annular recess 85 in theintermediate portion of the inner circumferential wall of the couplingring 81. The snap ring 84 is positioned in front of a forwardly facingradial shoulder 56 on the plug shell 11, cooperating with the flange 82in retaining the coupling ring 81 on the plug shell 11. This allows theCoupling ring 81 to rotate relative to the plug shell 11, but relativeaxial movement is prevented. 7

Intermediate the snap ring 841 and the flange 82, the coupling ring isprovided with three short, arcuate, longitudinally extending recesses 87in its inner surface 118 (see FlGS. 2 and 5). These recesses are adaptedto receive the outer rounded portion 69 of a leaf spring 90. The lattermember has normally straight legs 91 terminating in an inwardly bent end92 which is received within a radial opening 93 in the periphery of theplug shell. This holds the spring to the plug shell 11. Adjacent thelegs 91 of the spring 90 are flat chordal surfaces 94 which provide aclearance for permitting flexure of the spring 90.

By this construction, the coupling ring 81 can be ro tated relative tothe plug shell 11, but there is a detent action tending to preventrelative rotation when the portion 89 of the spring 90 enters a recess87. This retaining force may be overcome by applying adequate torque tothe coupling ring to cam the rounded spring portion 89 out of the recess87, compressing the spring inwardly and allowing the spring portion 89to slide along the circumferential surface 88 of the coupling ringintermediate the recesses 87.

Forwardly of the snap ring 84-, three bayonet grooves 95 are formed inthe inner circumferential surface 88 of the coupling ring. Each groove95 includes a wide entrance opening 96 at the forward end 97 of the coupling ring, from which there extends an inclined portion 98 ofthegroove, leading to a circumferential inner part 99 of the groove. Theaxis of the latter portion of the bayonet groove 95, as best seen inFIGS. 2 and 1 1, falls entirely within a radial plane as there is norecess for the bayonet pin at the inner end 100 of the groove.

The receptacle shell 65 includes a forward portion 101 of enlargeddiameter which provides a clearance around the insert assembly 61. Atthe end of the forward portion 101 of the receptacle shell are threeradi ally outwardly projecting bayonet pins 102.

When the electrical connector is to be mated, the forward end portion103 of the plug shell 11 enters the forward portion 101 of thereceptacle shell 65, fitting in the clearance space around the insertassembly 61 of the receptacle. Keys 104- on the plug shell fit inkeyways 105 in the receptacle shell, assuring the proper rotationalalignment of the plug and receptacle. With the keys in the keyways, thedetent spring, when in a recess 87 in the coupling ring, positions thecoupling ring so that the entrance 96 of the bayonet grooves 95 arealigned with the bayonet pins 102. Therefore, the bayonet pins 102 arebrought to the entrances 96 of the bayonet grooves 95 in the couplingring 81 as the plug and receptacle are advanced axially toward eachother. Subsequent rotation of the coupling ring 01 moves the bayonetpins 102 through the inclined portions 98 of the grooves 95 and into thecircumferential portions 99, drawing the plug and receptacle into thefully mated position. The coupling ring 81 is turned until the pins 102are adjacent the inner ends 100 of the grooves 95, which occurs as theouter portion 89 of the spring 90 enters a detent recess 87 in thecoupling ring.

A positive stop is provided in one of the bayonet grooves to preventrotation of the coupling ring 81 past the detent position when theconnector is mated. This is accomplished by bending inwardly a smallsection 106 of the circumferential wall of the coupling ring, presentingan abutment surface 107 in the bayonet groove where it can be contactedby the bayonet pin at the temperature of the rotation of the couplingring 81 (see FIG. 6). This location corresponds to the positioning ofthe outer portion 89 of the detent spring 90 in a detent receptacle $7.An opening W8 is formed in the wall of the coupling ring adjacent thestop W7, while two additional openings W9 in the coupling ring arespaced 120 from the opening Mid. This permits visual exterior inspectionof the connector when in the mated position to ascertain whether or notthe bayonet pins W2 have moved a sufficient distance into the bayonetgrooves 95. When the ends of the pins Hi2 (which may be painted) can beseen through the openings 108 and 109, it is known that the bayonet pinsare in the inner portions of the bayonet slots and that the plug andreceptacle are coupled properly.

By this arrangement, the plug and receptacle are advanced axially towardeach other the maximum distance when the bayonet pins are adjacent theends 109 of the grooves 95 that receive them. No outward movement occursas the connection is made, and, when the bayonet pins W2 reach thecircumferential portions 99 of the grooves 95, the parts are held intheir position of full maximum engagement. Even though subjected to aseparating force, no relative movement of the plug and receptacle cantake place, so that electrical continuity through the contacts isassured. The bayonet pins 102 are held against the forward sides of thebayonet grooves 95 when separating forces are imposed, while thecoupling ring 311 is prevented from movement axi ally by the engagementof the flange 82 with the rearwardly facing shoulder 83 of the plugshell lli. This provides a solid connection of the parts.

When the connector is in the fully mated position, the forward outerperiphery of the forward end of the plug shell llll engages an annularseal M0. The latter member is held in an annular groove 11111 in thereceptacle shell 65 by bonding.

In some instances, the snap ring 84 may be provided with forwardlyprojecting tabs U3 that are brought into engagement with the end of theforward portion ml of the receptacle shell 65 when the connector ismated (see FIG. This puts a desirable tension on the coupled plug andreceptacle, eliminating any clearance in the coupling mechanism. Thisalso makes an electrical connection between the plug shell ill and thereceptacle shell 65;

The plug and receptacle are disconnected by reverse rotation of thecoupling ring M to free the bayonet pins 102 from the bayonet grooves95. As this is accom plished, the detent spring is forced out of onedetent recess 87, and its central part 89 slides along the surface 88 ofthe coupling ring 81 to the next detent recess 87. in the latter detentposition, the bayonet pins H02 have reached the entrances 96 to thegrooves and the plug and receptacle may be pulled apart axially.

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims.

I claim:

ll. An electrical contact comprising a metal member having a rearwardtubular barrel for receiving and being connected to a wire, a forwardportion for engaging a mating contact, and an annular shoulder inwardlyof said forward portion, said shoulder facing rearwardly for engagementby retention fingers in holding said contact within an electricalconnector, said shoulder being inclined inwardly and toward said forwardportion.

2. A device as recited in claim 1 in which said shoulder is defined by afrustum of a cone.

3. A device as recited in claim 2 in which said shoul der is at an angleof approximately 12 to a plane radial relative to said contact.

4. A device as recited in claim 3 in which said member includes anannular enlargement, said shoulder being defined by the rearward edge ofsaid annular enlargement, said annular enlargement having asubstantially radial forward shoul-

1. An electrical contact comprising a metal member having a rearwardtubular barrel for receiving and being connected to a wire, a forwardportion for engaging a mating contact, and an annular shoulder inwardlyof said forward portion, said shoulder facing rearwardly for engagementby retention fingers in holding said contact within an electricalconnector, said shoulder being inclined inwardly and toward said forwardportion.
 2. A device as recited in claim 1 in which said shoulder isdefined by a frustum of a cone.
 3. A device as recited in claim 2 inwhich said shoulder is at an angle of approximately 12* to a planeradial relative to said contact.
 4. A device as recited in claim 3 inwhich said member includes an annular enlargement, said shoulder beingdefined by the rearward edge of said annular enlargement, said annularenlargement having a substantially radial forward shoulder.